2. Background Art
Since the inception of the wheelchair, manufacturers and users of this device have continually attempted to improve its comfort, operation, portability, and appearance. One area of ongoing concern is the capability of the wheelchair to exhibit excellent shock absorption characteristics while at the same time being cost-effective and light-weight. A suspension system, of the type similar to those that can be found on other types of wheeled vehicles such as cars and trucks, is incorporated in a vehicle for several reasons. One reason is to absorb shocks and thereby insulate from shocks the people and/or cargo being carried by the vehicle. For example, during use of a wheelchair, small bumps, depressions or other irregularities on the surface on which the wheelchair is traveling can cause such shocks. Another common objective of a vehicle suspension that also applies to wheelchairs is to maintain all of the wheels of the vehicle on the ground when such relatively small bumps or depressions are encountered, in order to maintain steering control and stability of the vehicle. However, unfortunately, many known suspension systems are too expensive and/or too heavy for incorporation into many of today""s lightweight and relatively inexpensive wheelchairs.
The present invention solves the above-described problems by incorporating a relatively simple, inexpensive, lightweight, yet effective suspension assembly adjacent to each wheel of the wheelchair, which in turn provides a relatively large amount of substantially vertical wheel displacement for absorbing shocks and for maintaining the steering control and stability of the wheelchair.
Objectives of the present invention include providing a wheelchair suspension system which absorbs and insulates the occupant of the wheelchair from shocks when relatively small bumps, depressions or other irregularities in a travel surface are encountered by the wheelchair.
Another objective of the present invention is to provide such a wheelchair suspension system in which all wheels of the wheelchair are maintained in constant contact with the travel surface when such bumps, depressions or other irregularities in the travel surface are encountered by the wheelchair, thereby maintaining occupant steering control and stability of the wheelchair.
A further objective of the present invention is to provide such a wheelchair suspension system which is economical to manufacture and install on a wheelchair, lightweight and reliable in use.
These objectives and advantages are obtained by the wheelchair suspension system of the present invention, the general nature of which may be stated as including at least one suspension system for a wheelchair, the suspension system including at least one suspension assembly interconnecting a frame of the wheelchair to an axle of at least one wheel of the wheelchair, the suspension assembly including top and bottom arms, each of the arms being pivotally and operatively attached at each of its ends to the frame and the axle; and a spring disposed between and attached to each of the arms, so that when the wheel encounters a bump in a travel surface, the arms pivot, the spring compresses and the axle moves in a substantially vertical upward direction, and when the wheel encounters a depression in a travel surface, the arms pivot, the spring is placed in tension and the axle moves in a substantially vertical downward direction.